DIGITAL EXCLUSIVEPublished : Oct 14, 2025 18:09 IST - 0 MINS READCOMMentsSHAREImage extracted from the Euclid Flagship simulations catalogue. Each dot represents a galaxy: blue points mark galaxies at the centres of dark matter clumps, while red points denote satellites within them. | Photo Credit: Jorge Carretero & Pau Tallada, Port d’Informació Científica/Euclid ConsortiumThe largest ever simulation of the universeEUCLID, the space telescope of the European Space Agency, has been surveying the cosmos with unprecedented resolution since its launch in July 2023.Its mission is to explore the composition and evolution of the dark universe (dark matter and dark energy). By measuring the positions and red shifts of billions of galaxies as far as 10 billion light years away, across more than a third of the sky, it will create a 3D map of the large-scale structure of the universe. The sheer volume and speed at which data points are produced by Euclid means that they must first be processed automatically. The methodology for interpreting these data had to be developed in advance, using simulations.On September 22, the Euclid Consortium, the international group that manages Euclid, released the largest synthetic simulation of the universe ever created. Called Flagship 2 galaxy mock, it contains 3.4 billion galaxies, each with 400 modelled properties such as brightness, position, velocity, and shape. The simulation is designed to help scientists interpret and analyse the massive datasets Euclid generated.The simulation is built on an algorithm developed by the astrophysicist Joachim Stadel of the University of Zurich (UZH). The calculation was carried out in 2019 on the supercomputer Piz Daint, the third most powerful supercomputer in the world at that time, at the Swiss National Supercomputing Centre in Lugano. More than 80 per cent of its total capacity was dedicated to the project. “It was a huge challenge to simulate such a large portion of the universe at this resolution in a single calculation,” Stadel said.The computation tracked the gravitational interactions of four trillion particles. In a second step, these structures were populated with galaxies that lie within Euclid’s field of view, producing a realistic blueprint of what Euclid will actually observe.The Flagship 2 simulation is based on the standard cosmological model and incorporates the current state of knowledge about the composition and evolution of the universe. While Stadel expects Euclid’s observations to broadly confirm the matter distribution predicted in the simulation, surprises and unexpected discoveries are anticipated. “We already see indications of cracks in the standard model,” said Stadel. Julian Adamek, Stadel’s collaborator from the UZH, added: “It will be exciting to see whether the model holds up against Euclid’s high-precision data.”The mission also aims to shed light on the nature of dark energy, the mysterious force driving cosmic expansion. In the model, dark energy is just a constant. Euclid’s data will enable astronomers to look back up to 10 billion years in cosmic history. “We can see how the universe expanded at that time and measure whether this constant really remained constant,” said Adamek.Euclid is the most comprehensive survey of the cosmos ever undertaken, not only in scale but also in precision. Its high resolution allows researchers to detect even minute distortions in galaxy images caused by gravitational lensing. These effects, produced by regions of high mass density bending light, reveal how invisible dark matter is distributed across the Universe.In March 2025, Euclid released the first observational dataset. This represented only a small fraction of the mission’s full dataset but already offered new insights into the cosmic web and galaxy clusters. The publication of further datasets is planned for the spring of 2026.Also Read | James Webb Space Telescope offers a window into the cosmos(Top left) 3D atomistic model of the graphene device, (bottom left) the top view of the actual device as seen under an optical microscope, and (right) an artist’s illustration of electrons moving like a fluid inside graphene. | Photo Credit: Aniket Majumdar, IIScMaking electrons move as a perfect fluid in grapheneWATER molecules are discrete particles but they flow collectively as liquid water. Although an electric current is also made of discrete electrons, they are so small that any collective behaviour among them is drowned out by larger influences as electrons pass through ordinary metals and semiconductors. The impurities and defects in the material and the vibrations among the material’s atoms influence the electron trajectories in the current.But, in certain materials and under specific conditions, such effects fade away, and electrons begin to interact with each other in such a way as to flow collectively as an electron fluid. Theory also predicts that in the absence of such ordinary, classical processes, quantum effects should take over with the electron-electron interaction being dictated by quantum mechanical effects and electrons flowing as a viscous quantum fluid. Such a behaviour was demonstrated in graphene—a 2D atom-thin sheet of pure carbon atoms—at near-zero temperatures in 2017.But a central quantum-theoretical question remained unanswered: Could electrons behave like a perfect, frictionless fluid with electrical properties described by a universal quantum attribute? For the first time, researchers at the Indian Institute of Science (IISc), along with collaborators from the National Institute for Materials Science, Japan, have detected this unique perfect quantum fluid of electrons in graphene.The researchers found that this exotic behaviour emerged when the number of electrons in the material is tuned close to what is called the “Dirac point”—an electronic tipping point where graphene is neither a metal nor an insulator—where electrons cease to act as individual charge carriers and move collectively as a fluid with extremely low viscosity, that is, almost like a frictionless perfect fluid. Such a quantum fluid state is called “Dirac fluid”.Alongside they also discovered the breakdown of a fundamental textbook principle that governs metals called the Weidemann-Franz law in this critical region, which states that electrical conductivity and thermal conductivity should be directly proportional. The team studied how ultraclean graphene conducted electricity and heat simultaneously. To their surprise, they found an inverse relationship between the two properties in dramatic violation of the law.In their graphene samples, the IISc team observed that the deviation from the law was more than a factor of 200 at low temperatures, demonstrating the near complete decoupling of charge and heat conduction mechanisms. A related significant discovery is that this decoupling is not random but that both charge and heat conduction depend on a material-independent universal constant that is equal to the quantum of conductance, a fundamental unit related to the motion of electrons.The findings were recently published in Nature Physics.“[The results] open a new window into the quantum realm and establish graphene as a unique tabletop laboratory for exploring hitherto unseen quantum phenomena. From a technological perspective, the presence of Dirac fluid in graphene also holds significant potential for use in quantum sensors capable of amplifying very weak electrical signals and detecting extremely weak magnetic fields,” the IISc press release said.CONTRIBUTE YOUR COMMENTSNew Story TitleAuthor NameJuly 17, 2024`; storyList.appendChild(newStoryItem); createDots(); dots = document.querySelectorAll(".dots .dot"); observer.observe(newStoryItem); } function removeStoryItem() { if (storyItems.length > 0) { storyList.removeChild(storyItems[storyItems.length - 1]); createDots(); dots = document.querySelectorAll(".dots .dot"); } }});]]>